1. Field of the Invention
This invention relates to a swivel mount device, more particularly to a ball-type swivel joint in which a ball-type swivel member is connected to a housing by a shaft.
2. Description of the Related Art
Referring to FIG. 1, a conventional swivel joint 1 is shown to include a swivel member 11, a housing unit 12, and a shaft 13. The swivel member 11 has a through hole 111. The housing unit 12 includes a housing 121 and a sleeve 122. The housing 121 has inner and outer tubular surfaces 123, 124, and two bearing holes 125 each extending through the inner tubular surface 123 and the outer tubular surface 124. The inner tubular surface 123 defines an accommodation chamber 126. The sleeve 122 has an inner sleeve wall surface 127 fittingly sleeved on the outer tubular surface 124. The shaft 13 extends through the through hole 111 and has two ends inserted respectively into the bearing holes 125 and retained by the sleeve 122. The inner sleeve wall surface 127 of the sleeve 122 is configured to match the outer tubular surface 124 of the housing 121 so that a tolerance therebetween is approximately 0, and can be sleeved fittingly on the housing 121 by a strong pressing force applied by a hydraulic press machine without any welding process. However, the following drawbacks arise:
1. The strong pressing force applied by the hydraulic press machine may scratch the outer surface of the swivel joint 1.
2. The sleeve 122 may be loosened and slip from the housing 121 after long-term use.
Reference is made to FIG. 2, which illustrates how another conventional swivel joint 2 is fabricated:
In step 201, a housing 21, a shaft 22, a coil spring 23, and a swivel member 24 are assembled. The housing 21 has an outer tubular surface 211 which includes an entry segment 212, a first shoulder abutment 213, a concaved segment 214, a second shoulder abutment 215, and a barrier segment 217 which are arranged in sequence. The first and second shoulder abutments 213,215 and the concaved segment 214 cooperatively define an annular groove 218. A first retaining corner 219 is formed between the first shoulder abutment 213 and the entry segment 212, and a second training corner 210 is formed between the second shoulder abutment 215 and the barrier segment 217.
In step 202, a sleeve 25 which has an inner diameter larger than the outer diameter of the concaved segment 214 is sleeved on the housing 21.
In step 203, a press machine is used to press a middle part of the sleeve 25 into the annular groove 218 such that the sleeve 25 is provided with a protrusion 251 that is disposed in the annular groove 218, and that has two ends abutting against the first and second retaining corners 219, 210, respectively.
In step 204, the sleeve 25 is subjected to surface treatment to smooth the outer surface thereof.
However, since surface treatment is required after all component parts of the swivel joint 2 are assembled, the manufacturing process is complicated. Moreover, chemical agents used in the surface treatment process may corrode the swivel member 24 and the shaft 22, so that swiveling of the swivel member 24 relative to the housing 21 may not be smooth.